Astaxanthin

Canthaxanthin biosynthesis by the conversion of methylene to keto groups in a hydrocarbon beta-carotene by a single gene.

Misawa N, Kajiwara S, Kondo K, Yokoyama A, Satomi Y, Saito T, Miki W, Ohtani T.

Central Laboratories for Key Technology, Kirin Brewery Co., Ltd., Kanagawa, Japan.

Compounds that include (a) keto group(s) in a molecule are ubiquitous natural components. A novel gene involved in ketocompound biosynthesis, designated crtW, was isolated from the marine bacteria Agrobacterium aurantiacum and Alcaligenes PC-1 that produce ketocarotenoids such as astaxanthin. When this gene was introduced into Escherichia coli that accumulated beta-carotene due to the Erwinia carotenogenic genes, the E. coli transformants synthesized canthaxanthin, one of ketocarotenoids, which was identified after purification by its visible, FD-MS and 1H-NMR spectral analysis. It has been demonstrated for the first time that one gene encodes an enzyme "ketolase" that catalyzes the conversion of methylene groups of a hydrocarbon beta-carotene to keto groups for synthesizing canthaxanthin via echinenone.

PMID: 7733978 [PubMed - indexed for MEDLINE]